Before replacing the ECU,
ensure that the communication circuit is normal.
JUDGMENT CRITERIA
The ETACS-ECU will set diagnosis code No. U1109 when no signals are received from the
column switch (column switch ECU).
PROBABLE CAUSES
Faulty wiper and washer switch
Malfunction of the LIN bus
DIAGNOSIS PROCEDURE
STEP 1. Resistance measurement at the column switch connector
(1)Disconnect the connector, and measure at the wiring harness side.
(2)Measure the resistance between the column switch connector (earth terminal) and
the body earth. OK: Continuity exists (2 Ω or less)
Q.
Is the check result normal?
Go to Step 3.
Go to Step 2.
STEP 2. Check of open circuit in body earth line between column switch
connector (earth terminal) and the body earth.
Q.
Is the check result normal?
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How
to use Troubleshooting/inspection Service Points - How to Cope with Intermittent
Malfunction ).
Repair the connector(s) or wiring harness.
STEP 3. Voltage measurement at the column switch connector.
(1)Disconnect the connector, and measure at the wiring harness side.
(2)Measure the voltage between the column switch connector (power supply terminal)
and the body earth. OK: System voltage
Q.
Is the check result normal?
Go to Step 5.
Go to Step 4.
STEP 4. Check of short to power supply, short to earth, and open circuit
in BUP1 line between ETACS-ECU connector and column switch connector.
Q.
Is the check result normal?
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How
to use Troubleshooting/inspection Service Points - How to Cope with Intermittent
Malfunction ).
Repair the connector(s) or wiring harness.
STEP 5. Check of open circuit in DATA line between ETACS-ECU connector
and column switch connector.
Q.
Is the check result normal?
Go to Step 6.
Repair the connector(s) or wiring harness.
STEP 6. Check whether the diagnosis code is reset.
Check again if the diagnosis code is set to the ETACS-ECU.
(1)Erase the diagnosis code.
(2)Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
(3)Check if diagnosis code is set.
Q.
Is the diagnosis code set?
Replace the wiper/washer switch.
A poor connection, open circuit, or other intermittent malfunctions in the LIN
bus lines between the column switch and the ETACS-ECU (Refer to GROUP 00 - How to Cope
with Intermittent Malfunction ).